WORK, ENERGY & POWER
Work
Work done on an object by a constant force, F, is F∆xcosθ where
F is the magnitude of the force, ∆x the magnitude of the
displacement and the angle between the force and the
displacement
W=F ∆x cosθ
The amount of work done in Joules = amount of energy transferred
Work is done on an object when the object moves in the same
plane as the force.
If a force is applied to an object at 90o to the motion of the object
then that force does no work on the object.
When a force is applied at an angle (θ) to an object then then work
is done by the component of the force that causes the object to
move.
This is given by the following equation: 𝑊 = 𝐹Δ𝑥𝑐𝑜𝑠 𝜃 W = work
done (J)
o F = force applied (N)
o Δx = displacement (m)
o θ = angle of force to the direction of motion
Work is a scalar quantity therefore it has magnitude but not
direction.
Work can be a negative value when the energy of the system
decreases and positive when the energy of the system increases.
Positive Work
Energy is transferred to the body increases energy of system
Depends on the angle between the force and the displacement
cos< 90°
Negative Work
Energy is transferred from the body decreases energy of system
Force is acting against the motion of the object, slowing it down
removing energy
90° < cos 180°
Zero Work
No work is done on an object when:
1. F = 0 N
2. x = 0 m
Work
Work done on an object by a constant force, F, is F∆xcosθ where
F is the magnitude of the force, ∆x the magnitude of the
displacement and the angle between the force and the
displacement
W=F ∆x cosθ
The amount of work done in Joules = amount of energy transferred
Work is done on an object when the object moves in the same
plane as the force.
If a force is applied to an object at 90o to the motion of the object
then that force does no work on the object.
When a force is applied at an angle (θ) to an object then then work
is done by the component of the force that causes the object to
move.
This is given by the following equation: 𝑊 = 𝐹Δ𝑥𝑐𝑜𝑠 𝜃 W = work
done (J)
o F = force applied (N)
o Δx = displacement (m)
o θ = angle of force to the direction of motion
Work is a scalar quantity therefore it has magnitude but not
direction.
Work can be a negative value when the energy of the system
decreases and positive when the energy of the system increases.
Positive Work
Energy is transferred to the body increases energy of system
Depends on the angle between the force and the displacement
cos< 90°
Negative Work
Energy is transferred from the body decreases energy of system
Force is acting against the motion of the object, slowing it down
removing energy
90° < cos 180°
Zero Work
No work is done on an object when:
1. F = 0 N
2. x = 0 m
